Definition
An energy microgrid is a local energy system that brings together distributed photovoltaics, an energy storage system, gas-fired heat and power, and smart meters. A community, park, or factory can use the energy on site, cover its own load, and export the surplus. It runs in parallel with the smart grid, can island, and can take part in demand response and peak shaving and valley filling, which raises how much of the energy is used and how reliably power is supplied. It is a core form of smart energy and of a low-carbon park.
Core Concepts and Technical Components
A microgrid usually includes distributed sources—distributed photovoltaics, wind, and gas generators; storage—an energy storage system (lithium, lead-acid, and similar) that smooths swings and does peak shaving and valley filling; load—buildings and smart-manufacturing lines; and monitoring and dispatch—smart meters and sensors that collect data, with a cloud platform using AI and machine learning to schedule the resources. Devices are linked and the data is uploaded over power-line carrier, WiFi, and similar links.
Use Cases
Energy microgrids are used in parks—industrial parks, science parks, and university towns; communities—residential areas and commercial complexes; factories—smart manufacturing and Industry 4.0 plants; and remote areas—off-grid or weak-grid supply. With demand response and peak shaving and valley filling, they can cut the electricity bill and qualify for demand-response subsidies. With smart meters, a cloud platform, and big data, the same site can manage energy in finer detail.
Technical Architecture and Implementation Path
The architecture has a device layer (distributed photovoltaics, storage, smart meters, and sensors), a communication layer (power-line carrier, WiFi, and industrial Ethernet), a platform layer (the cloud platform and a data processing engine), and an application layer (energy dispatch, peak shaving and valley filling, and demand response). A practical start is to install smart meters and collect data, then add distributed photovoltaics and storage, and only then build AI dispatch.
Implementation Guidance
Building an energy microgrid starts with an assessment of load and renewable resources, a design for the distributed photovoltaic and storage mix, smart meters and sensors, a connection to the cloud platform and the energy management system, and compliance with interconnection and safety rules. When selecting equipment, look at the interconnection interface with the smart grid, demand response, peak shaving and valley filling, and how open the API is. SimtoLink can supply smart meters, sensors, the cloud platform, and the API as one package for an energy microgrid.
Grid-tied operation, islanding, and power balance
An energy microgrid is a local system that balances distributed generation, storage, and load inside a defined electrical boundary. When it is grid-tied, it exchanges power with the external grid. When it is islanded, internal sources and storage have to hold voltage and frequency. The boundary usually sits at the interconnection switch. Technically it has to satisfy power balance, protection coordination, and switching logic at the same time. Grid-tied, it follows the external voltage. Islanded, it establishes voltage itself. At the instant of switching, internal sources must make up the power that disappears when the external grid is suddenly gone.
Source capacity, storage power, and important load inside the boundary have to be calculated in advance, including motor starts and other shocks. Protection settings must clear an internal fault, and must not mistakenly open the microgrid, or refuse to act, on an external fault. Black start must state which loads are energized first and which source establishes voltage first. Do not assume every device closes at once. Communication is for optimization and monitoring. The interconnection switch and protection should still act on local logic if communication stops. Metering should separate internal consumption, generation, and exchange with the outside. Otherwise the self-use share and settlement are both wrong.
Sizing equipment from annual average generation and consumption ignores the power shortfall at the switching instant. At the moment the external grid is lost, photovoltaics can supply almost none of the current needed to hold voltage, and voltage falls first. If storage power is enough and stored energy is not, the system can hold for a short time and still run short in a sustained island. Protection copied from an ordinary distribution network will not trip, because the fault current of a small internal source is not enough. An optimizer that sends economic power on a minute cycle, and fights a faster switch for control, causes oscillation or repeated connection and disconnection.
Being able to island for a short time does not mean every load can ride through. If non-critical load is not shed in stages, critical load is dragged down with it. A black-start sequence that has not been walked on site often stops at the supply of the first auxiliary machine. Do one planned short switch, and record voltage, frequency, the load that was shed, and the time of reconnection. Between distributed photovoltaics and the energy storage system, state who is in charge at the switching instant, so two controllers do not regulate the same inverter at once.